It is previously known to insert intramedullary nails into human skeletal bones e.g. when treating and fixating bone fractures, or correcting bone malalignments.
In numerous studies, intramedullary nailing has proved to be an effective and safe treatment for closed and grade I, II and IIIa open tibial shaft fractures. Intramedullary nailing has also been reported to be comparable to external fixation for treatment of grade IIIb open fractures.
The techniques and devices for intramedullary nailing have been improved, so that the time to union, the rate of infections, and the general function of the patient today are superior in comparison to other conventional treatment methods.
However, in the literature it has frequently been reported that patients can perceive anterior knee pain after the insertion of an intramedullary nail. Such anterior knee pain is a troublesome complication, which is especially painful when the patient is kneeling down. Therefore, it arises that patients in professions which require the use of such body positions are permanently disabled after the insertion of an intramedullary nail.
It has been found that nail insertion through the tendon more often results in anterior knee pain than if paratendinous insertion is used.
The etiology to the complication with anterior knee pain, however, is not clearly defined in the literature. Some authors have stated that the reason for the anterior knee pain is that an injured infrapatellar nerve produces a neuroma which causes the pain sensation. Others have claimed that the high position of the nail in relation to the anterior cortex and the tibial plateau are the reasons for the complication.
In a study by Hooper et al. (1991), concerns for the problem with anterior knee pain are expressed.
Furthermore, according to a study of Orfaly et al. (1995), 61 out of 107 patients (56%) developed troublesome knee pain in the area of nail insertion. When a paratendinous insertion was used, 33 out of 65 fractures (51%) were associated with subsequent knee pain. When nail insertion was performed through the tendon, 28 out of 36 knees (78%) developed subsequent pain. Orfaly et al. concluded that the nail position in relation to the anterior cortex and tibial plateau had no influence on the occurrence of knee pain, and that the response to nail removal was unpredictable.
Some authors, e.g. Zucman and Maurer (1970) recommend a longitudinal midline incision.
However, according to Court-Brown et al., a longitudinal midline incision might result in cutaneous nerve damage and significant keloid formation. Therefore, Court-Brown et al. propose the use of a transverse incision of approximately 3" (8 cm), which is made midway between the joint line and the tibial tubercle.
Mochida et al. studied the anatomic distribution of the infrapatellar branch of the saphenous nerve in cadavers, and investigated the incidence of injury to this branch in 68 patients after arthroscopic knee surgery. It was found that the safe incision area was within an area extending approximately 30 mm from the medial margin of the patella at the level of the midpatella, and within an area extending approximately 10 mm from the medial margin of the patella ligament at the level of the distal pole of the patella. In 30% of the examined cadavers it was found that the infrapatellar branch of the saphenous nerve extended transversely in a lateral direction before it crossed the proximal edge of the tibia.
Furthermore, it was found that the infrapatellar nerve extended at an angle of 45 degrees towards the articular surface of the tibia when the joint was extended, and almost horizontally and parallel to the articular surface when the joint was flexed 90 degrees.
In spite of the findings of the above-mentioned authors, there is still a need for a new method for percutaneous intramedullary nailing of tibial shaft fractures which reduces, and preferably eliminates the problem with anterior knee pain.
It is the belief of the present inventor that possible etiologies for anterior knee pain as a result of the previously known treatment methods include injury to the infrapatellar nerve and/or iatrogenic trauma to, or dissection around, the patellar tendon.